Support the eccentric clairvoyant (7)
I believe the answer is:
prophet
'clairvoyant' is the definition.
(thesaurus)
'support the eccentric' is the wordplay.
'support' becomes 'prop' (prop up can mean to support).
'eccentric' indicates an anagram.
'the' anagrammed gives 'het'.
'prop'+'het'='PROPHET'
(Other definitions for prophet that I've seen before include "Oracle" , "One who predicts the future" , "Augur" , "One who foretells the future as in the Bible" , "Religious leader" .)